1. Field of the Invention
The present invention relates to a liquid jet head that discharges a desired liquid by the creation of bubbles by the application of thermal energy which acts upon liquid. The invention also relates to a liquid jet recording apparatus that uses such liquid jet head, and a method for manufacturing such liquid jet heads.
Also, the present invention is applicable to a printer, a copying machine, a facsimile equipment provided with communication system, a word processor provided with a printing section, and some other apparatuses, as well as to an industrial recording system having various processing apparatuses combined complexly therefor, thus making it possible to record on paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramic, or some other recording media.
Here, for the present invention, the term "recording" referred to in the specification hereof means not only the provision of characters, graphics, or some other images that express some meaning when recorded on a recording medium, but also, means the provision of images that do not express any particular meaning, such as patterns recorded on a recording medium.
2. Related Background Art
There has been known conventionally an ink jet recording method, that is, the so-called bubble jet recording method, whereby to provide ink with heat or some other energy generated to cause change of states accompanied by the abrupt voluminal changes in ink (the creation of bubbles) so that ink is discharged from discharge openings on the basis of acting force exerted by such change of states, hence forming images on a recording medium by the adhesion of ink to it. The recording apparatus that uses this bubble jet recording method is generally provided with the ink discharge openings for discharging ink; the ink flow paths conductively connected with the discharge openings, and electrothermal transducing devices arranged in the ink flow paths as means for generating energy for discharging ink as disclosed in the specifications of U.S. Pat. No. 4,723,129 and others.
In accordance with a recording method of the kind, it is possible to record high quality images at high speeds in a lesser amount of noises. At the same time, it is possible to arrange the ink discharge openings in high density for the head that adopts this recording method. Therefore, images can be recorded in high resolution by use of a smaller apparatus, while making it easier to obtain color images, among many other advantages. As a result, the bubble jet recording method has been widely used for office equipment, such as a printer, a copying machine, or a facsimile equipment in recent years. Further, an ink jet textile printing apparatus that prints characters, specific patterns and designs on cloth has appeared on the market.
Most of the source documents used for a printer or a copying machine have been those containing monochrome characters, figures, or the like based on the binary data. However, along with the provision of color printers or the like, the graphics and photographs having intermediate gradation as to the density of colors, coloring or the like are used more increasingly for the source documents. The tendency that the printers, copying machines, and the like can appeal the general users good enough only with the capability of color handling at lower costs is now on the verge of shift. In the next stage, the weight is more on the provision of higher quality of images that may contain fine intermediate gradation in them.
The conventional ink jet recording apparatus uses the liquid jet head which is structured by laminating and bonding together a plurality of substrates provided with the heat generating devices (also, referred to as heaters), that is, the electrothermal transducing devices serving as means for creating bubbles, which are arranged in line side by side, and also, with the flow path walls that partition each of the heat generating devices thus arranged. Then, while optimizing the heater sizes, the heater positions, or the opening areas of discharge openings of each line, the heaters on each substrate is selectively controlled to make the amount of ink discharges variable in several steps for the provision of gradation on the recorded images.
However, since the conventional liquid jet head is structured by laminating and bonding a plurality of substrates together, its structure becomes more complicated, which necessitates more precision when manufacturing them, which raises a problem that the costs of manufacture are increased inevitably. Here, the complicated steps required for the manufacture of liquid jet heads tend to result in lowering the precision in which the heads should be produced. Then, there is a problem of production yield which may easily affect the costs of the manufacture, among some others.